1. Field of the Invention
The present invention relates generally to communications and, more particularly, to wireless communications.
2. Description of the Related Art
This section is intended to introduce the reader to various aspects of art that may be related to various aspects of the present invention, which are described and claimed below. This discussion is believed to be helpful in providing the reader with background information to facilitate a better understanding of the various aspects of the present invention. Accordingly, it should be understood that these statements are to be read in this light, and not as admissions of prior art.
One of the paramount challenges facing modern wireless telephone systems is the rapid growth of consumer demand for data services such as Internet access, text messaging, and e-mail. In fact, consumers are demanding greater access to data-related services than ever before, and this trend is not likely to change. For example, in the coming years, consumers will likely expect their wireless telephones to provide many, if not all, of the digital data communication features currently provided by computers (e.g., video conferencing, picture mail, etc.).
One method of transmitting digital data, such as digital photos, web pages, or videos, is with packets. A packet is a package of data capable of being routed through a computer network. Packets typically contain a packet header that contains the destination for the data, a payload that contains the data being transmitted, and some form of error checking information. Typically, a transmitting device will divide a message or file into a plurality of packets that will be transmitted across the network to a receiving device. The receiving device will then reassemble the packets into the original message or file. If one or more of the packets does not arrive at the receiver or arrives and cannot be decoded, the receiver can request a replacement packet from the transmitter. In this way, packetizing data may permit more efficient transmission of data by limiting the amount of data resent as a result of an error.
For the reasons stated above, packetizing data is a logical choice for transmitting data to a wireless unit or device. Over the past few years, a variety of systems have been developed to transmit packetized data over the cellular telephone network. These system include, but are not limited to, 1× Evolution Voice-Data Voice (“1× EV-DV”) in 3G1×, Evolution Voice-Data Only (“EV-DO”), and High Speed Downlink Packet Access (“HSDPA”) of Universal Mobile Telecommunication System (“UMTS”). Although the specific implementation details of each of these systems may vary, each adds at least one additional channel to carry packetized data. For example, 1× EV-DV includes a forward packet data channel (“F-PDCH”) to carry packetized data across a forward link between a base station and a wireless device.
In addition to packet data channels, packetized data transmission systems also typically include one or more control channels, referred to as packet assistant channels, to carry information that may facilitate or improve the transmission of data over the packet data channels. For example, 1× EV-DV includes a forward common power control channel (“F-RCCH”) that carries power commands to the mobile devices, a forward rate control channel (“F-RCCH”) that carries rate control information for the mobile device, a forward acknowledgement channel (“F-ACK”) that carries acknowledgement feedback for a reverse packet data channel, and a forward grant channel (“F-GCH”) that carries resource assignments associated with the reverse packet data channel.
Although the packet assistant channels facilitate the transmission of packetized data across the forward link, the data transmitted over the packet assistant channels still consumes base station transmission power. In fact, the packet assistant channels in combination with overhead channels, such as the pilot, paging, and sync channels may consume fifty percent or more of the base station's available transmission power in a 3G1× system, for example. Reducing the transmission power usage of the assistant channels may permit more of the base station's transmission power to be used to transmit the actual packetized data, which can increase the amount of digital data that can be transmitted to mobile devices. In the case of mixed voice and data on the same channel, reducing assistant channel power may also permit more of the base station's transmission power for voice calls.